They want Scotland to consider joining Norway, Switzerland, Iceland and Liechtenstein in EFTA, which has trade agreements with Europe but allows members to retain complete sovereignty.

Yesterday, EFTA senior information officer Tore Gronningsater said there had been no formal approach from the Scottish Government. But he predicted that Scotland would be welcomed into the organisation because it would be a “net contributor” and is a small nation which would not dominate the others.

Scotland could apply, but it would be a political question of whether the EFTA members would like to see more members

EFTA senior information officer Tore Gronningsater

He said: “Scotland could apply, but it would be a political question of whether the EFTA members would like to see more members. Just like the EU, this situation has never occurred for the last 20 or 30 years. It would have to be agreed by the other countries – but Scotland is not a dominant country like Turkey or the UK.”

Mr Gronningsater believes that joining EFTA would bring “several advantages” to Scots, should they vote to leave the UK.

He said: “Members do not have voting rights in the EU, but they do have to take on much of the legislation. However, the advantages are several.

“They did not have to become members of agricultural or fisheries policy, but they still get access to international markets and military co-operation [from the EU].

“There is an economic advantage as you are not paying into the full EU budget. EFTA has a structural fund, but net contributions are much lower.

“We also have 25 trade agreements with 35 different countries, including Russia, India and Indonesia.”

Last night, Mr Sillars welcomed the comments as “interesting” and added:

“What matters to us is to have access to the European market from day one of independence, and that would be the case if Scotland was a member of EFTA.

“Hearing their positive reaction, my advice to Alex Salmond would be to go away and speak to Norway.”

His wife, the independent MSP Margo MacDonald, plans to raise potential EFTA membership in this week’s First Minister’s Questions and will also contact Mr Gronningsater for further information.

She added: “I will write to the same information officer to request an assessment.

“It is incumbent on the First Minister to make sure that in the referendum people realise there is a choice to be made between London and Edinburgh and the EU and EFTA.

“It would help a lot of voters who are undecided because they do not want to be part of the EU if the EFTA membership was thoroughly investigated.”